US2576394A - Electrical apparatus - Google Patents

Description

Nov. 27, 1951 J. R. FREI ETAL ELECTRICAL APPARATUS 2 SHEETS-SHEET 1 Filed June 2, 1945 IN V EN TOR.

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1951 J- R. FREI ETAL 7 9 ELECTRICAL APPARATUS Filed June 2, 1945 2 SHEETSSl-IEET 2 ATTORNEY.

Patented Nov. 27, 1951 ELECTRICAL APPARATUS Jakob R. Frel and Charles W. Root, Sidney, N. Y., assignors to Bendix Aviation Corporation, New York, N. Y., a corporation of Delaware Application June 2, 1945, Serial No. 597,223

Claims.

This invention relates to a bank and plug selector of the type useful in controlling and testing the spark plug banks of internal combustion engines having a plurality of banks 01 radially aligned cylinders. The invention will be described in this particular use. but it is to be understood that this particular description is for purposes of illustration only and does not constitute a limitation within the natural scope of the invention.

Internal combustion engines of certain types used, for instance, in aircraft have radially projecting rows of cylinders, each row containing a plurality of cylinders and each cylinder adapted to be fired by a plurality of spark plugs, usually two to each cylinder. The left hand plugs in each row of cylinders are served by a magneto or by one coil of a double-coil magneto, the right hand plugs being served by a separate magneto or by the other coil of the double-coil magneto. In a radial engine having seven rows of cylinders with four cylinders to the row, there are thus 56 spark plugs, some of which may not be functioning. It is a time consuming labor to test each spark plug for purposes of replace ment, and it is highly desirable that some means he found whereby the spark plugs may be tested bank by bank in order that the pilot can readily determine what banks contain inoperative plugs. In this specification the term bank will be used to indicate those plugs which are connected with and fired by a single magneto coil. It is substantially impossible to locate an inoperative or misfiring cylinder by sound when so many plugs are functioning, but a trained pilot can frequently tell by sound when an engine of fewer cylinders is not properly functioning.

The foregoing statement is designed as a simple introduction to the complex problems which were met and overcome in the invention of the apparatus herein described. The great complexity of the problem will be better understood after the operation of the apparatus is comprehended from a study of the specification and drawings. It is within the conception of this invention to control the operation of the banks of spark plugs of an internal combustion engine by selectively grounding the magneto coils that serve the banks, and the invention will be described, for the sake of simplicity, as a means of grounding the primary windings of the magnetos.

It is an object of this invention to make a compact, sturdy instrument that may be simply and selectively operated to ground all primary windings of all the magneto coils that serve an internal combustion engine, to ground the primary windings of the magneto coils serving the right hand banks of spark plugs, to ground the primary windings of all the magneto coils serving the left hand banks of spark plugs, and to selectively ground the primary windings of individual magneto coils. Other objects of the invention will be in part apparent and in part set forth as the description of the invention proceeds.

The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 of the drawings is a vertical sectional view through a bank and plug selector embodying the principles of this invention;

Fig. 2 is a section on the line 22 of Fig. 1 looking in the direction of the arrows;

Fig. 3 is a section on the line 33 of Fig. 1 looking in the direction of the arrows;

Fig. 4 is a section on the broken line 4-4 of Fig. 1 looking in the direction of the arrows;

Fig. 5 is a bottom view of the casing showing the connection pins;

Fig. 6 is a top view of the casing, showing the head and dials;

Fig. 7 is a section showing details of switch construction with grounding contacts engaged; Fig. 8 is a section on the line 88 of Fig. 3;

Fig. 9 is a plan view of acontrol slot;

Fig. 10 is a section on the line |0-l0 of Fig. 9;

Fig. 11 is a view taken perpendicularly to a control slot on the upper segment of the ring member; and

Fig. 12 is a View taken perpendicularly to the ring member in a position degrees from Fig. 11.

Referring to the figures of the drawings, wherein like numerals refer to like parts, and particularly to Fig. l, the numeral l5 indicates a casing which is functionally designed to contain the operating parts of the apparatus, being comparatively small at its lower or base part and enlarged at the top or head end. A plug I6 is provided in the side of the casing cooperating with a groove in the member 20 for purposes of alignment. Injection of plastic insulating compounds after the assembling of the working parts has been completed is carried out through a hole in the center of member 33. The base I! of the casing I5 is flat and is provided with a hole l8 through which is passed the inner end 19 of a cylindrical member 20 having a flange 2| that is affixed to the flat end I! of easing l5 by rivets or the like 22. The outer portion 23 of the cylindrical member projects from the casing and is provided with screw threads or other suitable connecting means for the reception of a cable conduit or the like. Within the cylindrical member 20, mounted in insulating 3 material 24, are contact pins 25 (Fig. 5) which project both inwardly and outwardly beyond the insulating material to serve as appropriate connections for leads from the various magneto coils and for leads to the various contacts, to be hereinafter described. within the instrument.

In Fig. 5, sixteen contact pins 25 are illustrated, but since this description has been directed toward the control of an engine having 7 rows of cylinders and 14 banks of spark plugs, it will be understood that only 14 of the pins will be in use, each of the 14 magneto windings being connected by an appropriate lead to the outer end oi a pin. The inner ends of the pins are connected by appropriate leads 25 to two sets of switch contacts whose mounting and function will follow.

The inner wall of the casing i5 is provided with an annular shoulder 30 upon which rests the annular flange that projects from the ring 32 of a cup-shaped member 33. The cup-shaped member 33 is composed of insulating material such as anappropriate plastic, and carries upon the flange 3| an annulus 34 of insulating material that serves, in combination with the annular flange 3|, as a mounting for the leads 26 and the set of spring pressed contacts 35 projecting therefrom. Also connected to the leads 25 by appropriate leads 36 is a set of contacts 31 mounted in the ring 32 of the cup-shaped member 33.

The invention comprehends novel means for rendering all banks of plugs inoperative by grounding the primary windings of all magneto coils. In order to accomplish this control appropriate leads are brought from the primary windings of each magneto coil to the pins 25 and from pins 25 are connected by the leads 25 with spring pressed contacts 35 whose operative members are equal in number to the number of primary windings served, and means are provided whereby, by the simple turning of a switch, all the contacts 35. and the primary coils electrically connected thereto, may be grounded, thus preventing generation of induced currents in the secondary coils and making all the banks of spark plugs inoperative.

The leads 25 and 36 are attached at their ends to appropriate connections 40 in the annular flange 3|. The connections 40 comprise hollow pins. with conical recesses 42. The leads 35 have annular ends 43 that fit over the ends of the pins 4|, and are held in position by turning the ends of the pins over the ends of the leads. The insulation is stripped from the ends of wires 25, the wires are pushed through the hollow pins 4|, and their ends are soldered in the conical recesses. The soldered ends are simultaneously machined flush, making contact faces upon which rest springs 46. The annulus 34 is provided with recesses within hollow cylindrical bosses 45, mounted in places corresponding to the pins 4| and containing contacts 35 that are bi-' ased by springs 46. The outer ends of the bosses 45 are provided with inwardly directed annular flanges that cooperate with shoulders on the contacts 35 to prevent the springs 46 from ejecting the contacts from the sleeve. The same shoulders serve. internally, as seats for the springs 46, the other ends of which are based upon the machined faces of pins 4|. A plurality of mounting bolts 41 pass through the annulus 34 and the annular flange 3| into appropriate seats provided in the casing |5 to hold the parts firmly seated in assembled relation upon the shoulder 30.

Members 34 and 3| are separated by appropriate lands or studs formed on the face of one of them.

The spring contacts 35 are placed in a pattern on the annulus 34 so that by the use of a cooperating pattern on the movable switch member different groups of the contacts 35 may be selectively grounded. It will be observed that there are 15 such contacts shown in Fig. 3 of the drawings but it will be understood, since there are only 14 banks of spark plugs to be served, that one of these contacts is not connected to a magneto winding. In constructing the apparatus the pins 25 and the connections 40 are given letters. numbers, or other distinguishing identification so that the leads 26 may be correctly connected. The number of contacts will depend upon the number of electrical devices that are to be served by the apparatus, and the location and pattern of the contacts on flange 3| will be varied to achieve the most efficient operation under the particular circumstances of service.

Novel moving switch elements providing for the simultaneous grounding of all the contacts 35, are mounted in a head 50 that is mounted by appropriate bolts 5| on the large end of the casing i5. The head 50 has 'an internal annular flange 52 that serves to center it, and the instruments mounted therein, with respect to the cooperating fixed elements which are mounted in the member 33. The head 58 is centrally provided with an internally directed annular boss 53 having three enlargements 54 provided with seats 55 for spring pressed balls 56. Within the center annular portion of the boss 53 is revolvably mounted a cylindrical shaft 51 having an abutment flange 58 engaging the outer surface of the head 56 and havin an inner shoulder 59 serving as an abutment for the metal plate 60 that is mounted on and to turn with the inner end of the shaft 51. Lock nuts 6| serve for purposes of assembly of the parts. The inner end of the shaft 51 is flattened, as shown in Fig. 2, and the plate 60 is centrally provided with an opening 52 having cooperating flattened portions, whereby the turning of the shaft will turn the plate.

The central portion of the plate til is provided with holes 56 that are circularly aligned with the balls 56 and so spaced with relation thereto that as the plate is turned the balls 56 are thrust sequentially into the holes 65, giving the plate a plurality of fixed positions from which it can be displaced only by effort. In order to facilitate the turning of the shaft 51 and the plate 50, the outer end of the shaft is provided with a handle 55, and in order to limit its motion to a selected number of positions, stops 56, 61 are bent outward from the material of which the plate is made into cooperating relation with a stop 58 projecting inwardly from the head 50. The switch member is thereby provided with a number of fixed positions within a limited range of motion.

Aflixed to the inner face of the plate is an annulus In of insulatin material bearing on its inner surface a plurality of contacts ll each of which passes through an insulating ring and is aflixed to the plate 50. Because of their connection to the metal plate 60, these contacts are all grounded. The contacts H are arranged in a pattern that cooperates with the pattern of contacts 35, so that in various selected positions of the annulus l0 difierent groups of contacts 35 and the apparatus connected therewith will functioning.

be grounded. The apparatus illustrated is provided with four positions for the'handle 65 of the shaft 51, the four positions being indicated Within Fig. 6 as ofi," L, R and both. in the limits set by the stops 66, 61, 68 are four positions fixed by the ball positioning mechanism hereinbefore described, in the first of which the handle 65 points to the word off and every contact 35 is grounded through a contact 1|, as illustratively shown in Fig. '7. Since the contacts 35 are connected with the primary coils of the magnetos, all the magneto coils are grounded in this position of the switch and no current can be induced in the secondary windings thereof, and no current is being supplied to the spark plugs of the engine.

In the second position of the switch handle 65, shown as L in Fig. 6, the movable contacts have been shifted so that only half the contacts 35 are grounded through contacts 1|, the grounded contacts being all connected to the right-hand banks of spark plugs, so that the left-hand banks of spark plugs are free to function. In the third position R. as shown in Fig. 6, the movable contacts have again been shifted so that the left-hand banks of spark plugs are now grounded and the right-hand banks are It is therefore apparent that the mechanism as thus far described is capable of selectively operating the engine on either bank of plugs, or of making both banks of plugs inoperative. It is thus made possible for an operator to test the motor, first, with the left-hand banks of plugs operating, and then with the right-hand banks in operation. By cutting out half the plugs and comparing the operation of the engine under one bank with the operation of the engine under the other bank, a skilled operator can frequently locate sources of trouble in one or the other bank of plugs. In cases where such equipment is available, the power output of the two banks can be compared as a means of locating suspected trouble in one or the other bank.

The fourth position of the handle 65, indicated by the wor d both in Fig. 6, positions the ring 18 so that no contacts 35 touch any of the contacts 1| and no contacts 35 are grounded. In this position, therefore, both banks of spark plugs are operative. By this mechanism, therefore, there is provided a switch handle and a dial by means of which an operator can run on both banks of spark plugs, on either bank selectively, or can make both banks inoperative.

Novel means are also provided for the selective testing of individual banks of plugs in order that the operator may more accurately locate those defective plugs, or wiring, the presence of which was more generally indicated by the tests carried out on the right and left-hand banks operated as hereinbefore described. Means are therefore provided, which are normally held in inoperative position, for selectively testing the right and left plug banks of particular cylinder rows, comprising means for selecting a particular row of cylinders and associated means for grounding the right or left bank of spark plugs in that row. The ring 32 of the cup-shaped member 33 is provided with a number of contacts 31 corresponding to the number of coils that serve the plug banks; being in the case being described, fourteen in number. These contacts are circularly aligned, equally spaced about the circle, and mounted in holes in the ring 32. A ring 88 of insulating material closely fits the outside of the ring 32 and is provided with a series of smaller holes conforming in location to the holes in ring 3!. Each contact 31 has a part conforming to the size of the hole in ring 32 and a stud that passes through the smaller holes in ring and receives the end of a lead 36, so that each coil of the magneto is connected through a pin 25, a lead 26, and a lead 36 with a contact 31. As shown in Fig. 3, there are seven positioning grooves 82 formed in the inner circumference of the ring 32. These grooves as shown in Fig. 9, are broad and relatively deep near the open end of the ring member 33, are narrowed to a point flush with the inner circumference of the ring, and become progressively shallow toward the pointed end. The sides of the grooves are bevelled, the angle being easier toward the tip and more abrupt in the deeper portion of the groove. The purpose of these grooves is to position a novel rotatable switch member and to permit limited pivotal motion thereof so that contacts therein may selectively engage with the contacts 31 to ground individual coils.

Rotatably mounted within shaft 51 is a shaft 83 having a knurled finger knob 84 whereby it may be operated by hand, and a pointer 85 cooperating with the upper portion of the dial on the head 50 as shown in Fig. 6. The shaft 83 is normally held in the position shown in Fig. 1 by a coil spring 86 that bears at one end against the shaft 51 and at the other end against the switch head 81. The switch head 81 has a keyed mounting on the end of shaft 83 and is held in position thereon by bolt and washer 88 which are counterbored in the end of the switch head. The upper portion of the switch head is comparatively narrow as indicated in Fig. 3, and is provided with a spring pressed plunger or detent 89 and a spring pressed contact 90 which are aligned in parallel with the axis of the shaft 83. The lower part of the switch head is broader than the upper part and has a similar plunger 9| and contact 92 which are spring pressed but are not aligned in parallel with the axis of the shaft 83. The plunger 9| is positioned degrees from the plunger 89, but the contact 92 is not positioned 180 degrees frrm the contact 30.

In the normal inward position of the head 81, which is maintained by the spring 86, the plungers 89 and 9| ride upon the insulating material of the ring 32 out of the plane of contacts 31. The contacts 98 and 92 are likewise out of the plane of contacts 31 so that in the inward position of the switch head no contact will be made between contacts 98 and 92 and the contacts 31. In this position, therefore, the contacts 31 are entirely inefiective. The spring pressed plungers 89 and 9| ride in and cooperate with the tapered grooves 82, which because of their shape serve to give very fine control of the contacts 92 and 90.

When it is desired to test the right and left banks of a particular row of cylinders, the switch 65 may be turned to the both position and the knob 84 turned so that the pointer 85 indicates the row of cylinders that is to be tested. In Fig. 6, the pointer indicates row 3. Having selected the row that is to be tested, the knob 84 is pulled outwardly against the resistance of spring 86 and turned so that the pointer indicates the L" to the left of the number 3. When the pointer 85 indicates the number 3, the plunger 9!, or

awasca the contacts 90 and 92 in such position that, when shaft 83 is pulled outwardly, neither will touch a contact 31. In connecting the contacts 31 with the windings of the magnetos, care is taken to connect the right and left banks of each row to oppositely located contacts in the ring 32. Thus; as shown in Fig. 1, the two visible contacts 31 are respectively connected to the right and'left plug banks of cylinder row No. 3. When the shaft 83 has been pulled outward until the annular flange 93 rides upon the inner end of the shaft 51, the contacts 90 and 92 are aligned with the row of contacts 31, and the plunger 9| has entered the broad part of the groove 82, wherein it may be swun to the limits permitted by the side walls of the groove. By rotating the knob 84 to the left until the plunger reaches the wall Having tested the left bank, the operator may now rotate the knob 84' until the plunger reaches the other wall of the groove, in which position the pointer 85 indicates the letter R to the right of the number 3, thecontact 92 is withdrawn from its associated contact 31, and the contact 90 makes engagement with a contact 31 connected with the left-hand bank of plugs, leaving the right-hand bank in operation. 'In thisposition the operation of that bank can be observed, or tested if such apparatus is available. When the testing has been completed, the knob 84 may be released, and the spring 86 and the groove 82 will force the switch head to inoperative position.

When all the plug banks have been tested the knob 8-4 may be turned to the position in Fig. 6, in which position a stud 95 on the switch head passes under the over-turned end 96 of a stop 91, preventing the shaft 83 from being pulled outwardly into operative position. Stops 91 and 98 are attached to annulus 34 in such .position that the knob 84 cannot be turned beyond the .positions 0 and IR shown in Fig. 6. The contacts of the moving switch elements are grounded through shafts 51 and 88 andthe casing which is provided with a groundingscrew I00.

Figs. 11 and 12 are developments of the contact ring taken 180 apart in order to show diagrammatically the relation of grooves, contacts'and the plungers in head 81. In comparing these figures it should be remembered that motion of contact 90 to the left is accompanied by motion of the contact 92 to the right and vice versa.

The mechanism that has just been described enables an operator to ground each bank of plugs selectively, to ground the banks of plugs in groups, 1

to ground them all together, and to make. the grounding means inoperative so that all plugs are free to operate. These diverse and complex functions are accomplished by a mechanism having in effect only two moving parts, the motions of which are controlled on a single and simple dial. The apparatus is so constructed that individual plug banks cannot be left grounded after testing. The apparatus is sturdy and all the parts thGIBOf are capable" of withstanding rough usage. The method of mounting the studs 31 in the rings 32 and is novel and combinations of electrical devices.

it is to be observed that such expressions are not a limitation or a complete statement of all the details of novelty.

This invention has been described in connection with a particular use, namely the control of the plug banks of a multi-row radial engine, but it is to be understood that the invention may be employed in other connections where it is desired to selectively operate electrical instruments individually or in groups. For a defiinition of the limits of the invention, reference is had primarily to the appended claims.

What is claimed is:

1. Means for mounting a plurality of electrical contacts comprising an annulus of insulating material having a plurality of holes, and contacts projecting into said holes and havin integral projecting studs of a reduced diameter fixedly mounted in a ring of insulating material circumscribing and carried loosely by said annulus, said studs providing for connecting electrical leads to said contacts.

2. Means for mounting electrical contacts comprising inner and outer separable rings of insulating material having aligned holes of different sizes, and a contact mounted in said rings having portions conforming to the sizes of said aligned holes, the smaller portion of said contact providing for connecting an electrical lead to said contact and being peened over to make a firm connection to one of said rings.

3. Switch means for an electrical connection comprising a ring having a plurality of electrical contacts, a rotary switch operable within said ring to make contact selectively with said contacts, said rotary switch having oppositely disposed spring pressed members that make contact with the ring, and positioning grooves in said ring being in number half the number of the contacts and being so arranged that the said opposed spring pressed members make alternate contact with said positioning grooves.

4. In apparatus of the class described, a first set of fixed contacts, a second set of fixed contacts, common switch means having contacts movable individually into electrical operative relation with individual contacts of said first set of contacts, and common switch means having contacts movable collectively into electrical operative relation with a corresponding number of contacts of said second set of contacts.

5. In apparatus of the class described, a metallic casing, a first set of fixed contacts disposed within and insulated from said casing, a second set of contacts disposed within and insulated from said casing, common switch means disposed within and electrically connected with said casing and having contacts movable individually into engagement with individual contacts of said first set of contacts, and common switch means within and electrically connected with said casing and having contacts movable collectively into engageplurality of electrical contacts arranged in a pattern and of a number such that in three positions of said movable member all of said first-named contacts will be engaged by said second-named contacts, one-half only of said first-named contacts will be engaged by said second-named contacts, and the other half only of said first-named contacts will be engaged by said second-named contacts, respectively, and means for rotating said movable member to said positions.

7. In apparatus of the class described, a group of circumferentially spaced fixed contacts arranged within a ring of insulating material, oppositely positioned movable contacts disposed within and normally bearing on said ring, spring means for holding said movable contacts normally in inoperative postion, cooperating means on said ring and associated with said movable contacts providing for selection of said fixed contacts in pairs, means for moving said movable contactsin opposition to said spring means into operative relation with said fixed contacts and for thereafter moving said movable contacts selectively into contact with each contact of the selected pair of contacts.

8. In apparatus of the class described, a group of circumferentially spaced fixed contacts arranged within a ring of insulating material, an electrical switch positioned within said ring and mounted for rotary and axial movements relative to said ring, said switch having oppositely disposed contacts normally bearing on said ring, spring means for normally holding said switch in inoperative position, cooperating positioning grooves in said ring and oppositely disposed spring-pressed plungers on said switch providing for selection of said fixed contacts in pairs and for controlling the extent of rotation of said switch in opposite directions, and means for moving said switch axially in opposition to said spring means into operative relation with said fixed contacts and for thereafter rotating said switch in said directions to selectively engage said movable contacts with each contact of the selected pair of contacts.

9. In apparatus of the class described, a fixed cup-shaped member of insulating material having an external flange thereon, a first set of contacts circumferentially spaced in the wall of said cup-shaped member, a second set of contacts of a corresponding number arranged in an annular pattern in the outer surface of said flange and electrically connected with said first set of contacts, switch means for selectively placing said contacts individually or collectively in circuit comprising, a first rotary switch disposed within said cup-shaped member and having a contact movable to individually engage the-contacts of said first set of contacts, and a second rotary switch including an annular member disposed coaxially with said cup-shaped member and having on its adjacent inner surface a set of contacts arranged in an annular pattern and of a number such that in one position of said annular memher all of the contacts of said second set of contacts will be engaged by said second switch-contacts, and in another position one-half only of the contacts of said second set of contacts will be engaged by said second switch-contacts, and in another position the other half only of said second set of contacts will be engaged by said second switch-contacts, and means for rotating said first and second switches independently of each other.

10. In apparatus of the class described, a metallic casing, a fianged cup-shaped member of insulating material fixed within said casing, a first set of contacts arranged in an annular pattern on the outer surface of the flange of said cupshaped member, a second set of contacts of a corresponding number circumferentially arranged in the wall of said cup-shaped member and electrically connected with said first set of contacts, means for selectively establishing an electrical connection between said casing and said contacts individually or collectively comprising, a tubular metallic shaft disposed coaxially with said cup-shaped member and journalled in said casing, an annular metallic plate fixed on said shaft and having on its inner surface a set of contacts arranged, in an annular pattern and of a number such that in one annular position of said plate all of the contacts of said first set of contacts will be engaged by said plate-contacts, and in another annular position one-half only of the contacts of said first set of contacts will be engaged by said plate-contacts, and in another annular position the other half only of said first set of contacts will be engaged by said plate-contacts, and in still another annu lar position all of the plate-contacts will be disengaged from said first set of contacts, a metallic shaft mounted in said tubular shaft for rotary and axial movements and projecting therefrom toward said cup-shaped member, an annular metallic block disposed within said cup-shaped member and secured to said shaft, a contact on the periphery of said block, spring means for normally holding said shaft and said block in an inoperative axial position with said contact out of enga ement with said second set of contacts, means for moving said shaft and said block axially in opposition to said spring means to bring said contact into operative relation with said second set of contacts and for thereafter rotating said shaft and said block to engage said contact with individual contacts of said second set of contacts, and means for independently rotating said tubular shaft.

JAKOB R. FREI. CHARLES W. ROOT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,349,523" Middlebrook Aug. 10, 1920 1,414,734 Giovannoni May 2, 1922 1,721,286 Sweetman July 16, 1929 1,844,757 Greenwood Feb. 9. 1932 1,928,414 Douglas Sept. 26, 1933 1,956,430 Turner Apr. 24, 1934 1,969,867 Williams Aug. 14, 1934 2,121,124 Faulkner June 21, 1938 2,135,267 Alden Nov. 1, 1938 2,273,011 Batchelder Feb. 17, 1942 2,376,691 Hasselbaum May 22, 1945

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